Evaporative cooler media utilize liquid evaporation to cool air by contacting warm air with a liquid, such as water, causing the liquid to evaporate, thereby cooling the air. Evaporative cooler media are especially useful in arid areas having high temperatures and low humidities. Typical evaporative cooling systems include a high volume blower and at least one cooler pad supplied with water. The pads are porous to allow air to flow through, and water is absorbed/adsorbed by the pads or distributed on the pads to increase the surface area available for evaporation, with the blower blowing warm air through the pad to cool the air.
Various materials have been used in the prior art to form the cooler pads used in evaporative coolers. For example, Baigas, Jr., in U.S. Pat. No. 4,556,521, discloses a high loft batt (pad) of hydrophobic textile fibers such as polyester fibers, which are pre-bonded together and then coated with a preformed hydrophilic foam, which coats the bonded synthetic fibers and bridges and spans random portions of the interstices and passageways of the batt to increase the available surface area for contact by water. Preferred foams are formed of vinyl acetate homopolymers and/or polymeric acrylic emulsions.
Hobbs, in U.S. Pat. No. 4,902,449, forms an evaporative cooler pad from natural cellulosic light weight elongate segments, such as aspen wood shavings, which are oriented in generally horizontal planes which extend substantially parallel to the opposing faces of the pad. The cellulosic segments are coated with a hydrophilic foam to provide a coating thickness substantially less than the thickness of the elongate segments. The hydrophilic foam coating and surface has a minute cellular structure which produces a capillary type effect when contacted with water to whisk the water through the pad. All patents and other printed materials referred to herein are incorporated by reference as if reproduced in full hereinbelow. All information concerning chemicals used herein, trademarked or otherwise, is also incorporated by reference, such as but not limited to Material Safety Data Sheets discussing any chemicals mentioned herein.
Generally, evaporative cooler apparatus include an enclosure or housing in which an evaporative cooler pad is positioned so that water can be fed to the pad and air from a blower, located inside or adjacent to the enclosure, can be blown through the pad, thus cooling the air.
Unfortunately, prior art evaporative cooler media and evaporative cooler apparatus using the prior art media suffer from numerous deficiencies. For example, polyester fiber pads, which are formed of fibers coated with a hydrophilic coating, have too low a porosity and rapidly become clogged with dirt. Further, the polyester pads do not have sufficient dimensional stability or rigidity, and hence need greater reinforcement, such as by use of a reinforcement grid in the evaporative cooler apparatus housing. After several months of contact with water, the polyester fiber pads degenerate, and water causes them to collapse under their own weight if they are not replaced soon enough.
Prior art evaporative cooling pads formed from wood shavings also suffer from bacterial and fungal growth due to microorganisms carried by air circulated through the pads, which results in the pads giving off objectionable odors; further, bacterial action degrades the organic matter, causing the pads to sag, thus loosing the desired porosity for air passage, and reducing the surface area available for evaporation.
As the porosity of evaporative cooler pads decreases or as cooler pads become clogged in evaporative coolers, greater strain is placed on the blowers which draw or blow air through the cooler media; this results in increased energy consumption, increased wear on the blowers, or more frequent replacement of blowers. Therefore, there is a need for an improved evaporative cooling media having improved dimensional stability, high porosity, and high hydrophilicity, yet the media should not be subject to rapid bacterial or fungal decay and should be capable of being produced at a cost comparable to a conventional evaporative cooler media. There is also a need for an improved evaporative cooler apparatus utilizing such an improved cooler media, so that the apparatus will last longer and be more efficient in cooling, and yet require less frequent pad replacement.
To overcome some of these shortcomings, attempts were made to produce evaporative cooler media from inert inorganic or mineral fibers, such as those made of silica, and in particular, attempts were undertaken to form evaporative cooler media from fiber glass. Fiber glass mats are produced by melting glass to form long thin fibers and then winding of the fibers on a drum to form a mat. (This is known as hot melt spinning.) The mats are subsequently pulled or drawn to expand the mats into porous pads. Since prior art cooler pads had been produced by coating polyester fibers with an acrylic emulsion (otherwise known as an acrylic, acrylic polymer mixture, acrylic polymer blend, acrylic latex, latex, or acrylic resin), glass fibers were coated with an acrylic resin in an attempt to produce a hydrophilic, porous, glass fiber cooler media. However, the acrylic resin coating jelled onto the fibers in the glass fiber mat, and the glass fiber mats would not expand well into a pad (hence the resulting pads had zero or almost zero porosity).
Porous fiber glass pads are known, and are generally used as air filters. In order to form expanded, dimensionally stable high loft fiber glass pads from mats, the glass fibers are often coated with a binder during spinning, such as a urea-formaldehyde blend (otherwise known as urea-formaldehyde copolymer, UF, or urea-formaldehyde); however, binders such as urea-formaldehyde co-polymers degrade in water. Hence, such urea-formaldehyde bonded pads could not be used as evaporative cooler media, since the water would rapidly degrade the urea-formaldehyde which binds the fibers into a 3-dimensional porous matrix. Thus, early experiments failed to produce a hydrophilic glass fiber or hydrophilic glass fiber pads. (See U.S. Pat. No. 4,904,522 for binding of glass fiber mats with aqueous polyisocyanate emulsions for more information on glass fiber binding.)
Nevertheless, if a hydrophilic glass fiber could be produced and formed into a dimensionally stable porous pad, such pads would be highly useful in evaporative coolers and for other filtration purposes.
Therefore, it is a primary object of the present invention to produce a hydrophilic glass fiber.
It is a further object of the present invention to produce a dimensionally stable porous glass fiber pad having hydrophilic properties.
It is yet another object of the present invention to develop a method for forming hydrophilic glass fibers and dimensionally stable porous glass fiber pads having hydrophilic properties.
It is still yet another object of the present invention to provide an evaporative cooler apparatus utilizing a hydrophilic glass fiber cooling media.